In display devices such as liquid crystal display devices, a phase difference film may be used for, e.g., correcting a retardation (phase difference). The phase difference film may be a stretched film obtained by stretching a long-length pre-stretch film formed from a resin to orient molecules contained in the film. Such a stretched film is preferable because this can be easily produced.
Many studies have been made on such phase difference films formed from the stretched films. For example, there are known techniques such as those in Patent Literatures 1 to 4. Among these, Patent Literatures 1 to 3 disclose techniques for producing a phase difference film having inverse wavelength distribution property as a stretched film. The inverse wavelength distribution property is a property in which, as the wavelength of light passing through the phase difference film becomes longer, an in-plane direction retardation imparted to the light increases.